1. Field of the Invention
The present invention relates to the paper making art, and is more particularly concerned with a new and improved paper making machine dryer section drive and method.
2. Description of Prior Art
After the paper web has been dewatered in a paper making machine to the extent that it is self-supporting, the web to be dried is caused to travel through a dryer section having a plurality of rotatably mounted heated dryer drums or rolls arranged in cooperative upper and lower tiers and over which the paper web is adapted to travel in a sinuous path successively around the dryer rolls of the tiers. Respective dryer felts guide and hold the web onto the roll peripheral surfaces of each tier. Each dryer felt also functions to maintain substantial synchronism of the dryer rolls in the respective tier with which the felt is associated. Representative of this type of dryer section is the disclosure in U.S. Pat. No. 3,815,256.
In modern dryer sections, which may operate at lineal or machine direction speeds on the order of 3,000 feet per minute, it has been customary to drive the entire dryer section by means of one large driving motor and then through a long train of gears at the back side of the machine, all of the dryer rolls, which may be as many as fifteen in a typical dryer section, are driven in unison from the single motor. This requires a fairly massive and costly frame and gearbox arrangement, which interferes with cross machine moisture profile and symmetrical air flow from the paper machine basement, as well as interfering with broke removal, in contrast to the front side of the dryer section which is not encumbered with the gearbox structure. Because of the large number of gears in the train, considerable operating noise may be generated. Customarily, the gears are pressure lubricated with oil, and oil leakage can be a problem.
In addition, the gearing or transmission mechanism, housings, supports and pressure lubrication systems add a considerable expense to the cost of the paper machine installations.